1. Field of the Invention
The present invention relates to a non-volatile memory structure and a manufacturing method thereof, and more particularly, to a silicon-oxide-nitride-oxide-semiconductor (hereinafter abbreviated as SONOS) non-volatile memory structure and a manufacturing method thereof.
2. Description of the Prior Art
Semiconductor memory devices are prevalently used in computer and electronics industries as a means for retaining digital information. A typical semiconductor memory device includes a large number of memory elements, which is known as memory cells, for storing a single digital bit. Typically, the semiconductor memory devices are divided into volatile and non-volatile memory devices depending on whether the data stored in the memory devices is completely lost or not in case of power interruption.
In the conventional non-volatile memory technology, a SONOS memory structure is to build a silicon nitride layer sandwiched between two silicon oxide layers for serving as the charge trap layer while the two silicon oxide layers respectively serve as a charge tunnel layer and a charge block layer. This oxide-nitride-oxide (ONO) multilayered structure is further formed between a semiconductor substrate and a silicon control gate, and thus a SONOS memory structure is constructed. Since the ONO multilayered structure plays the essential role for storing data, it is always important to form a compact ONO structure and to improve the complicated method for manufacturing the memory structure.